NEW YORK — Ever wonder why a pair of reasonably decent eyeglass frames costs $250 or more while a pair of sunglasses of similar quality — complete with lenses — costs a fraction of that?

Or why high-end shopping areas and upscale malls across the nation are peppered with eyeglass stores?

Two words: huge profits.

That thinking — and the loss of a pair of glasses — was the genesis of Warby Parker, the online-based retailer that has exploded into the marketplace by selling stylish $95 frames complete with lenses.

"The technology behind a pair of glasses is 800 years old," says co-CEO Dave Gilboa at the company's headquarters in New York City's trendy SoHo neighborhood. "And it's kind of crazy you can buy a new iPhone for less than it costs to buy a pair of glasses."

Gilboa points to a virtual monopoly in the industry as the reason for high prices. "We thought it was kind of wacky how expensive glasses were," he says. "I lost my only pair of glasses while backpacking around Southeast Asia that had cost me $700. And I showed up at school without a pair of glasses … because it was hard for me to justify paying that much for a new pair."

Warby Parker is one of 10 finalists in USA TODAY's Entrepreneur of the Year contest. Profiles of the final contender will run this week, and a winner will be selected in December.

The enterprise — which started in 2010 when four graduates of the Wharton School at the University of Pennsylvania started selling glasses online from a Philadelphia apartment — has sold more than a million pairs. It has given the same number to charity as part of its "Buy a Pair, Give a Pair" program that benefits sight-impaired people in developing nations.

This has been a particularly big year for the company. The bricks-and-mortar operation has rapidly expanded from four stores to nine across the USA, and two more will launch in the next few months.

Part of the growth comes outside New York City, where most of the company's 400-plus employees are located. In September, Warby Parker announced the opening of corporate offices in Nashville, aiming to create about 250 jobs over the next five years. The retail stores operate coast to coast.

Another growth area: This year, the company introduced glasses with progressive lenses, priced at $295. "That makes up about 50% of the market in the U.S. that we hadn't been addressing," says Gilboa. who runs the company with co-CEO and fellow Wharton graduate Neil Blumenthal. (The other founders are involved in their own ventures, though they remain on the Warby Parker board.)

Overall sales — Gilboa says the vast majority of revenue is generated online — are growing at warp speed, aided by the firm's "Home Try-On" service that sends potential customers five pairs of glasses to try out for free, return postage paid. The privately held company doesn't disclose revenue, but Gilboa says June's announcement of a million glasses given away is an accurate indicator of sales. In July 2013, that figure was 500,000.

Warby Parker, named after two Jack Kerouac characters, Warby Pepper and Zack Parker, has done it all based on a four-pronged strategy: low prices, stylish glasses, social responsibility and customer service.

Wendy Liebmann of WSL Strategic Retail, a New York City-based industry analyst and consultant, says a key to success is that the firm has not been just a low-price competitor. "They discovered a problem, and they found a solution that wasn't the typical solution," Liebmann says, alluding to the company's emphasis on style and customer service.

She compares Warby Parker to Zappos, the online footwear retailer. "Nobody thought you could sell shoes without trying them on."

Zappos has certainly been an inspiration to Blumenthal and Gilboa, who mentions chats with Zappos CEO Tony Hsieh as key in focusing the company.

Gilboa's advice to new entrepreneurs: "Put customers first and … really focus on customer experience. We still to this day find that the majority of our customers learn about Warby Parker through word of mouth, through great experiences that other customers have had."

He advises against skimping on essentials. "We outsourced all our technology from the get-go and quickly realized that it was a massive mistake. If you want to be the most innovative brand and company … that has to start with technology."